Lockable differential gear

ABSTRACT

In a differential, a clutch links an axially stationary planet carrier with an axially mobile output shaft so that they rotate together. Engaging gears with engaging surfaces parallel to the main axis link an axially stationary clutch part with the output shaft so that they rotate together. Engaging gears with engaging surfaces parallel to the main axis link an axially mobile clutch part with the planet carrier so that they rotate together.

The invention relates to a differential gear having these features:

An axially stationary planet carrier drives two center gears over atleast one planetary gear,

each central gear drives an axially mobile output shaft,

at least one actuatable clutch with an axially stationary and an axiallymobile clutch component connects the planet carrier with an outputshaft.

the mobile clutch component is corotatably connected with the planetcarrier,

the stationary clutch component is corotatably connected with the outputshaft,

a gear housing has an intermediate ring part between a first and asecond main component,

the planet carrier is supported by a first bearing in the first maincomponent and by a second bearing in the intermediate ring part.

A differential of this kind is mostly used as a transversal differentialbetween the drive wheels of a drive axle and as a longitudinaldifferential between the two drive axles of a vehicle. The clutch has toprevent the skidding of a drive wheel on slippery ground.

When external forces, for instance of a universal joint between theoutput shaft and a steered drive wheel of the vehicle axially move theoutput shaft under full load, the axially parallel engaging surfaces ofthe engaging gears of the output shaft transmit high axial forcesthrough friction from the output shaft to the axially mobile clutchcomponent. In order to avoid these undesirable axial friction forces, ina known arrangement (DE-A-38 08 066, FIGS. 2 ad 3) the axially mobileclutch component is supported in the planet carrier by means of anengaging gear. The thereto pertaining actuation device for the clutch isa part of the differential gear. The axially stationary clutch componentwhich corotatably connected with the output shaft, is at the same timethe inner disk carrier of a friction clutch. Axial friction forces canhere act upon the friction disks and/or the bearing of the differentialgear.

In the differential gear with differential lock according to U.S. Pat.No. 2,017,577, the axially stationary clutch component is supported inthe axle housing by means of a radial ball bearing. This ball bearing isnot suitable for bracing against axial forces.

It is the object of the invention to create a differential gear of theaforedescribed kind, wherein the axially mobile clutch component and theaxially stationary clutch component are arranged so that disturbinginfluences originating from axial friction forces are excluded.

According to the invention, this problem is solved due to the fact thatthe stationary clutch component is held by two axial bearing axiallyfixed with respect to the second main component. This solution insuresthat the axially mobile as well as the axially stationary clutchcomponent are both free from axial friction forces, so that disturbinginfluences on one of the friction clutches of the differential gear,respectively the continuously controllable friction clutch for theconnection of the planet carrier with the output shaft are precluded.

A differential gear according to claims 2 and claim 3 can be controlledand adjusted so that it makes possible a free engine speed compensation(with minimal friction torque) as well as an actuation with full engineoutput over a single drive wheel (with maximum friction torque).

With the features according to claim 4 an actuatable clutch can be builtas a friction clutch with small dimensions, while the brakes areactuated as steering brakes, only thereby already preventing theskidding of a drive wheel.

With the features according to claim 5, it is enough to provide a singlebrake for at least two drive wheels, because the clutch transmits abraking torque of the brake to both output shafts of the differentialgear.

The drawing shows preferred embodiment examples of the invention.

FIG. 1 shows a first differential gear,

FIG. 2 shows a further differential gear,

FIG. 3 shows a differential gear according to claim 4,

FIG. 4 shows a differential gear according to claim 5.

FIG. 1: A planet carrier 1 of a differential gear 2 is supportedrotatably and axially stationary in a first bearing 3 in a first maincomponent 4 of a gear housing 5 and in a second bearing 6 in anintermediate ring component 7 of the gear housing 5. The planet carrier1 carries planetary gears 8 on a planet axle 9. The planet carrier 1drives a first and center gear 10, 11 over the planetary gears 8.

A first and a second friction clutch 12, 13 automatically connect theplanet carrier 1 with the first and second center gears 10, 11.

The first and the second center gear 10, 11 drive a first and a seconddrive wheel of the vehicle over a first and a second output shaft 14,15. Engaging gears with axially parallel engaging surfaces 16, 17corotatably connect the center gears 10, 22 with the axially mobileoutput shafts 14, 15.

An actuatable jaw clutch 18 with an axially stationary clutch component19 and an axially mobile clutch component 20 corotatably connect theplanet carrier 1 with the second output shaft 15. Axial bearings 21, 22hold the axially stationary clutch component 19 axially fixed to asecond main component 27 of the gear housing 5. Engaging gears withaxially parallel engaging surfaces 23 connect the axially stationaryclutch component 19 corotatably with the second output shaft 15. Theengaging gears with axially parallel engaging surfaces 24 corotatablyconnect the axially mobile clutch component 20 with the planet carrier1.

The clutch components 19, 20 together with the engaging gears withaxially parallel engaging surfaces 25, 26 form the shiftable jaw clutch18.

In the gear housing 5, axially between the intermediate ring part 7 andthe second main component 27 of the gear housing 5, a magnet coil 28 ofan electromagnet 29 is fastened. The axially mobile clutch component 20forms a magnet armature for the electromagnet 29. An electric current inthe magnet coil 28 generates a magnetic flux 30 and thereby an axialmagnetic force in a magnet gap 31 between a tapered surface 32 of theaxially mobile clutch component 20 and a tapered surface 33 of theintermediate ring part 7 of the gear housing 5 and closes the jaw clutch18 against a spring 34. The spring 34 and an axial bearing 35 areaxially arranged between the two clutch components 19, 20.

FIG. 2: A planet carrier 1 of a differential gear 2 is supportedrotatably and axially stationary in a first bearing 3 in a first maincomponent 4 of a gear housing 5 and in a second bearing 6 in anintermediate ring part 7 of the gear housing 5. The planet carrier 1drives via planetary gears 8 on a planet axle 9 a first and a secondcenter gear 10, 11. Engaging gears with axially parallel engagingsurfaces 16, 17 connect the axially stationary center gears 10, 11 withthe axially mobile output shafts 14, 15.

A continuously controllable friction clutch 36 with an axiallystationary clutch component 19 and an axially mobile clutch component 20can transmit a continuously controllable friction torque between theaxially stationary planet carrier 1 and the axially mobile second outputshaft 15.

Axial bearings 21, 22 with bearing races 58, 59 hold the axiallystationary clutch component 19 axially fixed with respect to the gearhousing 5. Engaging gears with axially parallel engaging surfaces 23connect the axially stationary clutch component 19 in a corotationalmanner with the second output shaft 15. Engaging gears with axiallyparallel engaging surfaces (24) corotatably connect the axially movableclutch component 20 with the planet carrier 1. The friction clutch 36 isa disk clutch with outer disks 37 in an outer disk carrier and innerdisks 38 on an inner disk carrier. The axially stationary clutchcomponent 19 forms the inner disk carrier. The axially mobile clutchcomponent 20 forms the outer disk carrier.

The intermediate ring part 7 of the gear housing 5 forms a cylinder fora piston 39 and with the piston 39 a chamber 40. Sealing rings 41, 42seal radially between the piston 39 and the intermediate ring part 7.Pressure fluid in the chamber 40 pushes the piston 39 via an axialbearing 43 against the axially mobile clutch component 20 and theaxially mobile clutch component 20 via the outer disks 37 and the innerdisks 38 against the axially stationary clutch component 19, therebygenerating a friction torque of the friction clutch 36.

FIG. 3: A differential gear according to FIG. 2 is here completed by twobrakes 45, 46.

A first brake 45 transmits a continuously controllable braking torquefrom the first output shaft 14 to the first main component 4 of the gearhousing 5. A second brake 46 transmits a continuously controllablebraking torque from the second output shaft 15 to the second maincomponent 27 of the gear housing 5.

Each brake 45, 46 is a disk brake with outer disks 47 in an outer diskcarrier 49 and with inner disks 48 on an inner disk carrier 50. Eachinner disk carrier 50 is corotatably connected with an output shaft 14,15, via engaging gears with axially parallel engaging surfaces 57. Eachouter disk carrier 49 is fixed in main component 4, 27 of the gearhousing 5. Each outer disk carrier 49 forms a cylinder for a piston 51and with the piston 51 a chamber 52 for pressure fluid. Sealing rings53, 54 seal radially between the piston 51 and the outer disk carrier49. Pressure fluid in chamber 52 pushes the piston 51 against an axiallymobile first end member 55 and the first end member 55 via outer disks47 ad inner disks 48 against an axially stationary second end member ofthe brake 45, 56, thereby generating the braking torque of brake 45, 46.

The bearing flange 44 of the first bearing 3 for the planet carrier 1forms the second end member of the first brake 45. A thrust ring 56 forthe axial bearing 21 for the first clutch component 19 of the frictionclutch 36 is fixed in the second main component 27 of the gear housing 5and forms the second end member of the second brake 46.

FIG. 4: A continuously controllable friction clutch 36 with an axiallystationary clutch component 19 and an axially mobile clutch component 20transmits a continuously controllable friction torque between theaxially stationary planet carrier 1 and the axially mobile output shaft15.

A brake 60 transmits a continuously controllable braking torque from theplanet carrier 1 to the first main component 4 of the gear housing 5.The brake 60 is a disk brake with outer disks 61 in an outer diskcarrier and inner disks 62 on an inner disk carrier 63. The first maincomponent 4 of the gear housing 5 forms the outer disk carrier. Theinner disk carrier 63 is connected with the planet carrier 1 in a fixedbut detachable manner. The first main component 4 of the gear housing 5forms a cylinder for the piston 64 and with the piston 64 a chamber 65.The piston 64 forms an actuating member for the brake 60. Pressure fluidin chamber 65 via the piston 64 pushes together the outer disks 61 andthe inner disks 62 against a fixed end member 66 and generates a brakingtorque of the brake 60.

Besides the four embodiment examples shown in the drawing, within theframework of the invention many more different constructions arepossible, wherein the features of claim 1 are combined in a differentway with the features defined in the other claims.

For instance, the differential gear 2 shown in FIG. 1 with the jawclutch 18 can be additionally provided with two brakes 45, 46 as shownin FIG. 3. Or one of the differential gears 2 shown in FIG. 2 or in FIG.3 can additionally be equipped on the other side of the planet carrier 1with a second intermediate ring part and with a second friction clutch,connecting the planet carrier 1 with the first output shaft 14 in acorotational manner.

Or the first and second main components 4, 27 form additionally theouter disk carriers 49 for the outer disks 47 and the cylinder for thepiston 51 (FIG. 3). Or vice versa, a special component is fastened inthe gear housing 5 and forms the outer disk carrier for the outer disks61 and the cylinder for the piston 64. (FIG. 4).

Pressure fluid for the chambers 40, 52 and 65 for the friction clutch 36(FIGS. 2 to 4) and the brakes 45, 56 (FIG. 3) and 60 (FIG. 4) can bedelivered by any desired source. The pressure fluid can be a liquid or agas.

    ______________________________________                                                  Reference Numerals                                                  ______________________________________                                                   1 planet carrier                                                              2 differential gear                                                           3 bearing                                                                     4 main component                                                              5 gear housing                                                                6 bearing                                                                     7 intermediate ring part                                                      8 planetary gear                                                              9 planet axle                                                                10 center gear                                                                11 center gear                                                                12 friction clutch                                                            13 friction clutch                                                            14 output shaft                                                               15 output shaft                                                               16 engaging surface                                                           17 engaging surface                                                           18 jaw clutch, clutch                                                         19 clutch component                                                           20 clutch component                                                           21 axial bearing                                                              22 axial bearing                                                              23 engaging surface                                                           24 engaging surface                                                           25 engaging surface                                                           26 engaging surface                                                           27 main component                                                             28 magnet coil                                                                29 electromagnet                                                              30 magnet flux                                                                31 magnet gap                                                                 32 tapered surface                                                            33 tapered surface                                                            34 spring                                                                     35 axial bearing                                                              36 friction clutch, clutch                                                    37 outer disks                                                                38 inner disks                                                                39 piston                                                                     40 chamber                                                                    41 sealing ring                                                               42 sealing ring                                                               43 axial bearing                                                              44 bearing flange                                                             45 brake                                                                      46 brake                                                                      47 outer disk                                                                 48 inner disk                                                                 49 outer disk carrier                                                         50 inner disk carrier                                                         51 piston                                                                     52 chamber                                                                    53 sealing ring                                                               54 sealing ring                                                               55 end member                                                                 56 thrust ring                                                                57 engaging surface                                                           58 bearing race                                                               59 bearing race                                                               60 brake                                                                      61 outer disk                                                                 62 inner disk                                                                 63 inner disk carrier                                                         64 piston                                                                     65 chamber                                                                    66 end member                                                       ______________________________________                                    

We claim:
 1. Differential gear having these features:An axiallystationary planet carrier (1) drives two center gears (10, 11) over atleast one planetary gear (8), each center gear (10, 11) drives anaxially mobile output shaft (14, 15), at least one actuatable clutch (18or 36) with an axially stationary and an axially mobile component (19,20) connects the planet carrier (1) with an output shaft (15), thestationary clutch component (19) is corotatably connected with theoutput shaft (15), a gear housing (5) has an intermediate ring part (7)between a first and a second main component (4, 27); the planet carrier(1) is supported by a first bearing (3) in the first main component (4)and by a second bearing (6) in the intermediate ring part (7), themobile clutch component (20) is corotatably connected with the planetcarrier (1), characterized by these features: the stationary clutchcomponent (19) is supported by two axial bearings (21, 22) axially fixedwith respect to the second main component (27).
 2. Differential gearaccording to claim 1 with the following features:The actuatable clutch(36) is a friction clutch; the intermediate ring part (7) forms acylinder for a piston (39) and with the piston (39) a chamber (40);pressure fluid in the chamber (40) produces a friction torque of theclutch (36).
 3. Differential gear according to claim 2 with thefollowing features:The clutch (36) is a disk clutch with outer disks(37) in an outer disk carrier and inner disks (38) on an inner diskcarrier; the mobile clutch component (20) forms the outer disk carrier;the stationary clutch component (19) forms the inner disk carrier. 4.Differential gear according to claim 1 having the following features:Afirst brake (45) connects a first output shaft (14) with the first maincomponent (4); a second brake (46) connects the second output shaft (15)with the second main component (27).
 5. Differential gear according toclaim 2 having the following features:a brake (60) connects the planetcarrier (1) with the first main component (4); a logical circuitcontrols the friction coupling (36) when the brake is actuated.